Wing spar



July 7, 1925. 1,544,861

R. E. ROBILLARD WING SPAR Filed March 12, 1925 anueufoz Patented July 7, 1925.

ROBERT 'E. ROBILLARD, OF BELLEVILLE, ILLINOIS.

WING SPAR.

Application filed March 12, 1923. Serial No. 624,654.

To all 'whom it may concern:

Be it known that 1, ROBERT E. ROBILLARD,

a citizen of the United States, residing at Belleville', in the county of St. Clair and State of Illinois, have invented certain new and useful Improvements in Wing Spars, of which the following is a specification.

This invention relates to wing spars, the same being designed primarily for use as a structural beam or spar for aeronautical purposes and being especially designed for use in the formation and setting up of the main spars of an aerofoil or wing structure. The structure isalso admirably adapted for fuselage and body construction.

The main object of the invention is to produce a light weight spar of the character above referred to in which the metal portions of the spar are so disposed as to give the greatest lateral and vertical rigidity or stilfness combined with minimum weight.

A further object of the invention is to effect economy of material through concentrating the material at the outermost or lateral portions of the truss; to adapt the spar to quantity production, the same being attained by reason of the simple sections used, the ease of assembly of the parts of the spar, and the elimination of complicated supplies.

Additionally, the wing spar herein fully described and shown, is statically determinate and should therefore be very simple to design after a study resulting from a few experimental tests.

With the above and other objects in view the invention consists in the novel construction, combination and arrangement herein fully described, shown and claimed.

In the accompanying drawings- Figure 1 is a fragmentary side elevation of the improved wing spar;

Figure 2 is a vertical transverse section through the same;

Figure 3 is a fragmentary vertical transverse section taken through the lower longitudinal in line with one point of connection with the main web or truss;

Figure 4 is a fragmentary plan view showing one of the splices in a lo 'itudinal.

While the spar or beam herein own and described is partly designed for use as a wing spar in an aerofoil section, such as is now commonly used in airplanes, it will be apparent, as the description .proceeds,""that the structure may be usedfor other pur poses in connection with aeronautical work.

For the sake of illustration, however, the lnvention is shown applied in the formation of one of the main spars of the supporting surface of an airplane.

The spar comprises upper and lower longitudinals 1 and 2 and the main connecting web 3 of truss-like formation. Each of the longitudinals is composed of two lateral tubular portions 4 and a centrally connecting web or plate-like portion 5. Each longitudinal may be formed either by rolling a large tube into shape, shown in Fig; 2 and fastening the meeting portions of the plate-like part of the longitudinal by suitable fastening means 6, such as rivets or bolts; or the longitudinal may be formed out of a piece of sheetmetal bent to the required shape, as shown in Fig. 2 and riveted or otherwise fastened together or united alon the connecting or web-like portion of the fimgitudinal.

The main web or truss-like portion of the completespar is formed, preferably of a single continuous tube, as shown, the same being bent at intervals in the length thereof and flattened to provide abutments or seats 7 which bear against the plate-like portions .5 of the longitudinals 1 and 2, such platelike' portions 7 being fastened to the longitudinals by any suitable means, such as rivets or bolts 8. To produce an extra long longitudinal the sections of the longitudinal may be spliced in the'manner shown in Fig. 4 wherein it will be seen that one of the meeting and overlapping ends is cut away to form a recess 9 adapted to receive the adjacent plate-like portion 5 of the abutting and overlappin end of the adjacent section. The tubeike portions ofthe sections fit telescopically one within the other and are secured together by a fastening means, such as rivets or any other desired manner as indicated in Fig. 4, wherein the overlapping extremities of the sections are shown tseparated for the sake of better illustra- By reason of the construction herein shown and described, increased lateral rigidity is obtained, material is economized. through concentrating the. same at theoutermost portions of the truss, the structure is partly adapted to quantity production by reason-of the simple sections used, the ease of assembly of the sections and the avoidance' of complicated splices. Furthermore,

the spar is statically determinate and is i simple to desi n for any type or sized careof the longitudinals cut away to receive the fully after a few experimental tests. plate of the adjacent longitudinal and the 10 What I claim is tubularportions of one of the longitudinals A joint for the meeting ends of the receiving the ends of the tubular portions 5 longitudinals of a wing spar, each longiof the adjacent longitudinal.

tudinal composed of substantially parallel In testimony whereof I affix my signature. tubular portions, a plate connecting said tubular portions, the plate at the end of one ROBERT E. ROBILLARD. 

